Assessment of left ventricular function at rest and analysis of arrhythmias prior to hospital dischargge allows prediction of a portion of the 10-15% of patients who will die suddenly within six months of discharge after acute myocardial infarction. Using new non-invasive radionuclide cineangiographic techniques, which permit study during exercise and hence provide more complete assessment of cardiac function than previously available, we propose to determine the feasibility of improving prognostic capability after acute myocardial infarction. Better prediction might allow appropriate application of medical and surgical therapy prophylactically in high risk patients.